1. Field of the Invention
The present invention relates to a body shake and twist exerciser and, in particular, to improvements relating to the transmission mechanism in a vertical type shake and swing exerciser for waist twist exercises by the user.
2. Prior art of the Invention
There are many kinds of equipment used in waist twist exercises, of which the most commonly seen are hula hoops and twist discs. In a known calisthenics apparatus for hip twisting waist girdling exercises, the transmission mechanism consists of a cross bar (rotating arm) having a downward projecting shaft on one end capable of being freely rotatably engaged in a bearing seat at the center of the base and an upward projecting bearing seat on the other end. A rotating disc is freely rotatably engaged in the upward projecting bearing seat on the one end of the cross bar by a central downward projecting shaft. When a user holds onto a guardrail set up above and around the base and steps with both feet onto the rotating disc to twist and swing the waist to the left and right sides, this rotating disc is rotated with the bearing seat on the free end of the cross bar as the center of rotation. Because of the human body weight and the forces produced by rotative force of the rotating disc, the cross bar also rotates about the bearing seat of the base. In other words, relative to the center of the base this rotating disc appears to be eccentric and while the disc rotates about its center it also rotates around the base center. This type of motion is frequently observed in physical teaching game apparatus in science museums and in rotary cups in children's amusement parks.
When the aforesaid exerciser with the above-described mechanism is actually used for exercises it will be found that because there is no relation between the rotating disc and the cross bar (rotary arm), each performs rotation about its axis in an arbitrary and irregular direction and manner. As a result, the user cannot easily maintain a standing position in a specified direction leading to uncontrollable body distortion. Particularly, as the speed of the separate rotary motion of the two rotating parts increases this will result in the movement being difficult to follow, the movement getting confused, the body of the user being unable to stand firmly and the user will have a tendency to fall off. To prevent the user from falling off, it has been suggested to mount an additional waist girdling ring having three directional supports to maintain the user's the center of gravity equilibrium.